xref: /freebsd/contrib/less/decode.c (revision 2b15cb3d0922bd70ea592f0da9b4a5b167f4d53f)
1 /*
2  * Copyright (C) 1984-2012  Mark Nudelman
3  *
4  * You may distribute under the terms of either the GNU General Public
5  * License or the Less License, as specified in the README file.
6  *
7  * For more information, see the README file.
8  */
9 
10 
11 /*
12  * Routines to decode user commands.
13  *
14  * This is all table driven.
15  * A command table is a sequence of command descriptors.
16  * Each command descriptor is a sequence of bytes with the following format:
17  *	<c1><c2>...<cN><0><action>
18  * The characters c1,c2,...,cN are the command string; that is,
19  * the characters which the user must type.
20  * It is terminated by a null <0> byte.
21  * The byte after the null byte is the action code associated
22  * with the command string.
23  * If an action byte is OR-ed with A_EXTRA, this indicates
24  * that the option byte is followed by an extra string.
25  *
26  * There may be many command tables.
27  * The first (default) table is built-in.
28  * Other tables are read in from "lesskey" files.
29  * All the tables are linked together and are searched in order.
30  */
31 
32 #include "less.h"
33 #include "cmd.h"
34 #include "lesskey.h"
35 
36 extern int erase_char, erase2_char, kill_char;
37 extern int secure;
38 
39 #define SK(k) \
40 	SK_SPECIAL_KEY, (k), 6, 1, 1, 1
41 /*
42  * Command table is ordered roughly according to expected
43  * frequency of use, so the common commands are near the beginning.
44  */
45 
46 static unsigned char cmdtable[] =
47 {
48 	'\r',0,				A_F_LINE,
49 	'\n',0,				A_F_LINE,
50 	'e',0,				A_F_LINE,
51 	'j',0,				A_F_LINE,
52 	SK(SK_DOWN_ARROW),0,		A_F_LINE,
53 	CONTROL('E'),0,			A_F_LINE,
54 	CONTROL('N'),0,			A_F_LINE,
55 	'k',0,				A_B_LINE,
56 	'y',0,				A_B_LINE,
57 	CONTROL('Y'),0,			A_B_LINE,
58 	SK(SK_CONTROL_K),0,		A_B_LINE,
59 	CONTROL('P'),0,			A_B_LINE,
60 	SK(SK_UP_ARROW),0,		A_B_LINE,
61 	'J',0,				A_FF_LINE,
62 	'K',0,				A_BF_LINE,
63 	'Y',0,				A_BF_LINE,
64 	'd',0,				A_F_SCROLL,
65 	CONTROL('D'),0,			A_F_SCROLL,
66 	'u',0,				A_B_SCROLL,
67 	CONTROL('U'),0,			A_B_SCROLL,
68 	' ',0,				A_F_SCREEN,
69 	'f',0,				A_F_SCREEN,
70 	CONTROL('F'),0,			A_F_SCREEN,
71 	CONTROL('V'),0,			A_F_SCREEN,
72 	SK(SK_PAGE_DOWN),0,		A_F_SCREEN,
73 	'b',0,				A_B_SCREEN,
74 	CONTROL('B'),0,			A_B_SCREEN,
75 	ESC,'v',0,			A_B_SCREEN,
76 	SK(SK_PAGE_UP),0,		A_B_SCREEN,
77 	'z',0,				A_F_WINDOW,
78 	'w',0,				A_B_WINDOW,
79 	ESC,' ',0,			A_FF_SCREEN,
80 	'F',0,				A_F_FOREVER,
81 	ESC,'F',0,			A_F_UNTIL_HILITE,
82 	'R',0,				A_FREPAINT,
83 	'r',0,				A_REPAINT,
84 	CONTROL('R'),0,			A_REPAINT,
85 	CONTROL('L'),0,			A_REPAINT,
86 	ESC,'u',0,			A_UNDO_SEARCH,
87 	'g',0,				A_GOLINE,
88 	SK(SK_HOME),0,			A_GOLINE,
89 	'<',0,				A_GOLINE,
90 	ESC,'<',0,			A_GOLINE,
91 	'p',0,				A_PERCENT,
92 	'%',0,				A_PERCENT,
93 	ESC,'[',0,			A_LSHIFT,
94 	ESC,']',0,			A_RSHIFT,
95 	ESC,'(',0,			A_LSHIFT,
96 	ESC,')',0,			A_RSHIFT,
97 	SK(SK_RIGHT_ARROW),0,		A_RSHIFT,
98 	SK(SK_LEFT_ARROW),0,		A_LSHIFT,
99 	'{',0,				A_F_BRACKET|A_EXTRA,	'{','}',0,
100 	'}',0,				A_B_BRACKET|A_EXTRA,	'{','}',0,
101 	'(',0,				A_F_BRACKET|A_EXTRA,	'(',')',0,
102 	')',0,				A_B_BRACKET|A_EXTRA,	'(',')',0,
103 	'[',0,				A_F_BRACKET|A_EXTRA,	'[',']',0,
104 	']',0,				A_B_BRACKET|A_EXTRA,	'[',']',0,
105 	ESC,CONTROL('F'),0,		A_F_BRACKET,
106 	ESC,CONTROL('B'),0,		A_B_BRACKET,
107 	'G',0,				A_GOEND,
108 	ESC,'>',0,			A_GOEND,
109 	'>',0,				A_GOEND,
110 	SK(SK_END),0,			A_GOEND,
111 	'P',0,				A_GOPOS,
112 
113 	'0',0,				A_DIGIT,
114 	'1',0,				A_DIGIT,
115 	'2',0,				A_DIGIT,
116 	'3',0,				A_DIGIT,
117 	'4',0,				A_DIGIT,
118 	'5',0,				A_DIGIT,
119 	'6',0,				A_DIGIT,
120 	'7',0,				A_DIGIT,
121 	'8',0,				A_DIGIT,
122 	'9',0,				A_DIGIT,
123 	'.',0,				A_DIGIT,
124 
125 	'=',0,				A_STAT,
126 	CONTROL('G'),0,			A_STAT,
127 	':','f',0,			A_STAT,
128 	'/',0,				A_F_SEARCH,
129 	'?',0,				A_B_SEARCH,
130 	ESC,'/',0,			A_F_SEARCH|A_EXTRA,	'*',0,
131 	ESC,'?',0,			A_B_SEARCH|A_EXTRA,	'*',0,
132 	'n',0,				A_AGAIN_SEARCH,
133 	ESC,'n',0,			A_T_AGAIN_SEARCH,
134 	'N',0,				A_REVERSE_SEARCH,
135 	ESC,'N',0,			A_T_REVERSE_SEARCH,
136 	'&',0,				A_FILTER,
137 	'm',0,				A_SETMARK,
138 	'\'',0,				A_GOMARK,
139 	CONTROL('X'),CONTROL('X'),0,	A_GOMARK,
140 	'E',0,				A_EXAMINE,
141 	':','e',0,			A_EXAMINE,
142 	CONTROL('X'),CONTROL('V'),0,	A_EXAMINE,
143 	':','n',0,			A_NEXT_FILE,
144 	':','p',0,			A_PREV_FILE,
145 	't',0,				A_NEXT_TAG,
146 	'T',0,				A_PREV_TAG,
147 	':','x',0,			A_INDEX_FILE,
148 	':','d',0,			A_REMOVE_FILE,
149 	'-',0,				A_OPT_TOGGLE,
150 	':','t',0,			A_OPT_TOGGLE|A_EXTRA,	't',0,
151 	's',0,				A_OPT_TOGGLE|A_EXTRA,	'o',0,
152 	'_',0,				A_DISP_OPTION,
153 	'|',0,				A_PIPE,
154 	'v',0,				A_VISUAL,
155 	'!',0,				A_SHELL,
156 	'+',0,				A_FIRSTCMD,
157 
158 	'H',0,				A_HELP,
159 	'h',0,				A_HELP,
160 	SK(SK_F1),0,			A_HELP,
161 	'V',0,				A_VERSION,
162 	'q',0,				A_QUIT,
163 	'Q',0,				A_QUIT,
164 	':','q',0,			A_QUIT,
165 	':','Q',0,			A_QUIT,
166 	'Z','Z',0,			A_QUIT
167 };
168 
169 static unsigned char edittable[] =
170 {
171 	'\t',0,	    			EC_F_COMPLETE,	/* TAB */
172 	'\17',0,			EC_B_COMPLETE,	/* BACKTAB */
173 	SK(SK_BACKTAB),0,		EC_B_COMPLETE,	/* BACKTAB */
174 	ESC,'\t',0,			EC_B_COMPLETE,	/* ESC TAB */
175 	CONTROL('L'),0,			EC_EXPAND,	/* CTRL-L */
176 	CONTROL('V'),0,			EC_LITERAL,	/* BACKSLASH */
177 	CONTROL('A'),0,			EC_LITERAL,	/* BACKSLASH */
178    	ESC,'l',0,			EC_RIGHT,	/* ESC l */
179 	SK(SK_RIGHT_ARROW),0,		EC_RIGHT,	/* RIGHTARROW */
180 	ESC,'h',0,			EC_LEFT,	/* ESC h */
181 	SK(SK_LEFT_ARROW),0,		EC_LEFT,	/* LEFTARROW */
182 	ESC,'b',0,			EC_W_LEFT,	/* ESC b */
183 	ESC,SK(SK_LEFT_ARROW),0,	EC_W_LEFT,	/* ESC LEFTARROW */
184 	SK(SK_CTL_LEFT_ARROW),0,	EC_W_LEFT,	/* CTRL-LEFTARROW */
185 	ESC,'w',0,			EC_W_RIGHT,	/* ESC w */
186 	ESC,SK(SK_RIGHT_ARROW),0,	EC_W_RIGHT,	/* ESC RIGHTARROW */
187 	SK(SK_CTL_RIGHT_ARROW),0,	EC_W_RIGHT,	/* CTRL-RIGHTARROW */
188 	ESC,'i',0,			EC_INSERT,	/* ESC i */
189 	SK(SK_INSERT),0,		EC_INSERT,	/* INSERT */
190 	ESC,'x',0,			EC_DELETE,	/* ESC x */
191 	SK(SK_DELETE),0,		EC_DELETE,	/* DELETE */
192 	ESC,'X',0,			EC_W_DELETE,	/* ESC X */
193 	ESC,SK(SK_DELETE),0,		EC_W_DELETE,	/* ESC DELETE */
194 	SK(SK_CTL_DELETE),0,		EC_W_DELETE,	/* CTRL-DELETE */
195 	SK(SK_CTL_BACKSPACE),0,		EC_W_BACKSPACE, /* CTRL-BACKSPACE */
196 	ESC,'\b',0,			EC_W_BACKSPACE,	/* ESC BACKSPACE */
197 	ESC,'0',0,			EC_HOME,	/* ESC 0 */
198 	SK(SK_HOME),0,			EC_HOME,	/* HOME */
199 	ESC,'$',0,			EC_END,		/* ESC $ */
200 	SK(SK_END),0,			EC_END,		/* END */
201 	ESC,'k',0,			EC_UP,		/* ESC k */
202 	SK(SK_UP_ARROW),0,		EC_UP,		/* UPARROW */
203 	ESC,'j',0,			EC_DOWN,	/* ESC j */
204 	SK(SK_DOWN_ARROW),0,		EC_DOWN,	/* DOWNARROW */
205 	CONTROL('G'),0,			EC_ABORT,	/* CTRL-G */
206 };
207 
208 /*
209  * Structure to support a list of command tables.
210  */
211 struct tablelist
212 {
213 	struct tablelist *t_next;
214 	char *t_start;
215 	char *t_end;
216 };
217 
218 /*
219  * List of command tables and list of line-edit tables.
220  */
221 static struct tablelist *list_fcmd_tables = NULL;
222 static struct tablelist *list_ecmd_tables = NULL;
223 static struct tablelist *list_var_tables = NULL;
224 static struct tablelist *list_sysvar_tables = NULL;
225 
226 
227 /*
228  * Expand special key abbreviations in a command table.
229  */
230 	static void
231 expand_special_keys(table, len)
232 	char *table;
233 	int len;
234 {
235 	register char *fm;
236 	register char *to;
237 	register int a;
238 	char *repl;
239 	int klen;
240 
241 	for (fm = table;  fm < table + len; )
242 	{
243 		/*
244 		 * Rewrite each command in the table with any
245 		 * special key abbreviations expanded.
246 		 */
247 		for (to = fm;  *fm != '\0'; )
248 		{
249 			if (*fm != SK_SPECIAL_KEY)
250 			{
251 				*to++ = *fm++;
252 				continue;
253 			}
254 			/*
255 			 * After SK_SPECIAL_KEY, next byte is the type
256 			 * of special key (one of the SK_* contants),
257 			 * and the byte after that is the number of bytes,
258 			 * N, reserved by the abbreviation (including the
259 			 * SK_SPECIAL_KEY and key type bytes).
260 			 * Replace all N bytes with the actual bytes
261 			 * output by the special key on this terminal.
262 			 */
263 			repl = special_key_str(fm[1]);
264 			klen = fm[2] & 0377;
265 			fm += klen;
266 			if (repl == NULL || (int) strlen(repl) > klen)
267 				repl = "\377";
268 			while (*repl != '\0')
269 				*to++ = *repl++;
270 		}
271 		*to++ = '\0';
272 		/*
273 		 * Fill any unused bytes between end of command and
274 		 * the action byte with A_SKIP.
275 		 */
276 		while (to <= fm)
277 			*to++ = A_SKIP;
278 		fm++;
279 		a = *fm++ & 0377;
280 		if (a & A_EXTRA)
281 		{
282 			while (*fm++ != '\0')
283 				continue;
284 		}
285 	}
286 }
287 
288 /*
289  * Initialize the command lists.
290  */
291 	public void
292 init_cmds()
293 {
294 	/*
295 	 * Add the default command tables.
296 	 */
297 	add_fcmd_table((char*)cmdtable, sizeof(cmdtable));
298 	add_ecmd_table((char*)edittable, sizeof(edittable));
299 #if USERFILE
300 	/*
301 	 * For backwards compatibility,
302 	 * try to add tables in the OLD system lesskey file.
303 	 */
304 #ifdef BINDIR
305 	add_hometable(NULL, BINDIR "/.sysless", 1);
306 #endif
307 	/*
308 	 * Try to add the tables in the system lesskey file.
309 	 */
310 	add_hometable("LESSKEY_SYSTEM", LESSKEYFILE_SYS, 1);
311 	/*
312 	 * Try to add the tables in the standard lesskey file "$HOME/.less".
313 	 */
314 	add_hometable("LESSKEY", LESSKEYFILE, 0);
315 #endif
316 }
317 
318 /*
319  * Add a command table.
320  */
321 	static int
322 add_cmd_table(tlist, buf, len)
323 	struct tablelist **tlist;
324 	char *buf;
325 	int len;
326 {
327 	register struct tablelist *t;
328 
329 	if (len == 0)
330 		return (0);
331 	/*
332 	 * Allocate a tablelist structure, initialize it,
333 	 * and link it into the list of tables.
334 	 */
335 	if ((t = (struct tablelist *)
336 			calloc(1, sizeof(struct tablelist))) == NULL)
337 	{
338 		return (-1);
339 	}
340 	expand_special_keys(buf, len);
341 	t->t_start = buf;
342 	t->t_end = buf + len;
343 	t->t_next = *tlist;
344 	*tlist = t;
345 	return (0);
346 }
347 
348 /*
349  * Add a command table.
350  */
351 	public void
352 add_fcmd_table(buf, len)
353 	char *buf;
354 	int len;
355 {
356 	if (add_cmd_table(&list_fcmd_tables, buf, len) < 0)
357 		error("Warning: some commands disabled", NULL_PARG);
358 }
359 
360 /*
361  * Add an editing command table.
362  */
363 	public void
364 add_ecmd_table(buf, len)
365 	char *buf;
366 	int len;
367 {
368 	if (add_cmd_table(&list_ecmd_tables, buf, len) < 0)
369 		error("Warning: some edit commands disabled", NULL_PARG);
370 }
371 
372 /*
373  * Add an environment variable table.
374  */
375 	static void
376 add_var_table(tlist, buf, len)
377 	struct tablelist **tlist;
378 	char *buf;
379 	int len;
380 {
381 	if (add_cmd_table(tlist, buf, len) < 0)
382 		error("Warning: environment variables from lesskey file unavailable", NULL_PARG);
383 }
384 
385 /*
386  * Search a single command table for the command string in cmd.
387  */
388 	static int
389 cmd_search(cmd, table, endtable, sp)
390 	char *cmd;
391 	char *table;
392 	char *endtable;
393 	char **sp;
394 {
395 	register char *p;
396 	register char *q;
397 	register int a;
398 
399 	*sp = NULL;
400 	for (p = table, q = cmd;  p < endtable;  p++, q++)
401 	{
402 		if (*p == *q)
403 		{
404 			/*
405 			 * Current characters match.
406 			 * If we're at the end of the string, we've found it.
407 			 * Return the action code, which is the character
408 			 * after the null at the end of the string
409 			 * in the command table.
410 			 */
411 			if (*p == '\0')
412 			{
413 				a = *++p & 0377;
414 				while (a == A_SKIP)
415 					a = *++p & 0377;
416 				if (a == A_END_LIST)
417 				{
418 					/*
419 					 * We get here only if the original
420 					 * cmd string passed in was empty ("").
421 					 * I don't think that can happen,
422 					 * but just in case ...
423 					 */
424 					return (A_UINVALID);
425 				}
426 				/*
427 				 * Check for an "extra" string.
428 				 */
429 				if (a & A_EXTRA)
430 				{
431 					*sp = ++p;
432 					a &= ~A_EXTRA;
433 				}
434 				return (a);
435 			}
436 		} else if (*q == '\0')
437 		{
438 			/*
439 			 * Hit the end of the user's command,
440 			 * but not the end of the string in the command table.
441 			 * The user's command is incomplete.
442 			 */
443 			return (A_PREFIX);
444 		} else
445 		{
446 			/*
447 			 * Not a match.
448 			 * Skip ahead to the next command in the
449 			 * command table, and reset the pointer
450 			 * to the beginning of the user's command.
451 			 */
452 			if (*p == '\0' && p[1] == A_END_LIST)
453 			{
454 				/*
455 				 * A_END_LIST is a special marker that tells
456 				 * us to abort the cmd search.
457 				 */
458 				return (A_UINVALID);
459 			}
460 			while (*p++ != '\0')
461 				continue;
462 			while (*p == A_SKIP)
463 				p++;
464 			if (*p & A_EXTRA)
465 				while (*++p != '\0')
466 					continue;
467 			q = cmd-1;
468 		}
469 	}
470 	/*
471 	 * No match found in the entire command table.
472 	 */
473 	return (A_INVALID);
474 }
475 
476 /*
477  * Decode a command character and return the associated action.
478  * The "extra" string, if any, is returned in sp.
479  */
480 	static int
481 cmd_decode(tlist, cmd, sp)
482 	struct tablelist *tlist;
483 	char *cmd;
484 	char **sp;
485 {
486 	register struct tablelist *t;
487 	register int action = A_INVALID;
488 
489 	/*
490 	 * Search thru all the command tables.
491 	 * Stop when we find an action which is not A_INVALID.
492 	 */
493 	for (t = tlist;  t != NULL;  t = t->t_next)
494 	{
495 		action = cmd_search(cmd, t->t_start, t->t_end, sp);
496 		if (action != A_INVALID)
497 			break;
498 	}
499 	if (action == A_UINVALID)
500 		action = A_INVALID;
501 	return (action);
502 }
503 
504 /*
505  * Decode a command from the cmdtables list.
506  */
507 	public int
508 fcmd_decode(cmd, sp)
509 	char *cmd;
510 	char **sp;
511 {
512 	return (cmd_decode(list_fcmd_tables, cmd, sp));
513 }
514 
515 /*
516  * Decode a command from the edittables list.
517  */
518 	public int
519 ecmd_decode(cmd, sp)
520 	char *cmd;
521 	char **sp;
522 {
523 	return (cmd_decode(list_ecmd_tables, cmd, sp));
524 }
525 
526 /*
527  * Get the value of an environment variable.
528  * Looks first in the lesskey file, then in the real environment.
529  */
530 	public char *
531 lgetenv(var)
532 	char *var;
533 {
534 	int a;
535 	char *s;
536 
537 	a = cmd_decode(list_var_tables, var, &s);
538 	if (a == EV_OK)
539 		return (s);
540 	s = getenv(var);
541 	if (s != NULL && *s != '\0')
542 		return (s);
543 	a = cmd_decode(list_sysvar_tables, var, &s);
544 	if (a == EV_OK)
545 		return (s);
546 	return (NULL);
547 }
548 
549 #if USERFILE
550 /*
551  * Get an "integer" from a lesskey file.
552  * Integers are stored in a funny format:
553  * two bytes, low order first, in radix KRADIX.
554  */
555 	static int
556 gint(sp)
557 	char **sp;
558 {
559 	int n;
560 
561 	n = *(*sp)++;
562 	n += *(*sp)++ * KRADIX;
563 	return (n);
564 }
565 
566 /*
567  * Process an old (pre-v241) lesskey file.
568  */
569 	static int
570 old_lesskey(buf, len)
571 	char *buf;
572 	int len;
573 {
574 	/*
575 	 * Old-style lesskey file.
576 	 * The file must end with either
577 	 *     ...,cmd,0,action
578 	 * or  ...,cmd,0,action|A_EXTRA,string,0
579 	 * So the last byte or the second to last byte must be zero.
580 	 */
581 	if (buf[len-1] != '\0' && buf[len-2] != '\0')
582 		return (-1);
583 	add_fcmd_table(buf, len);
584 	return (0);
585 }
586 
587 /*
588  * Process a new (post-v241) lesskey file.
589  */
590 	static int
591 new_lesskey(buf, len, sysvar)
592 	char *buf;
593 	int len;
594 	int sysvar;
595 {
596 	char *p;
597 	register int c;
598 	register int n;
599 
600 	/*
601 	 * New-style lesskey file.
602 	 * Extract the pieces.
603 	 */
604 	if (buf[len-3] != C0_END_LESSKEY_MAGIC ||
605 	    buf[len-2] != C1_END_LESSKEY_MAGIC ||
606 	    buf[len-1] != C2_END_LESSKEY_MAGIC)
607 		return (-1);
608 	p = buf + 4;
609 	for (;;)
610 	{
611 		c = *p++;
612 		switch (c)
613 		{
614 		case CMD_SECTION:
615 			n = gint(&p);
616 			add_fcmd_table(p, n);
617 			p += n;
618 			break;
619 		case EDIT_SECTION:
620 			n = gint(&p);
621 			add_ecmd_table(p, n);
622 			p += n;
623 			break;
624 		case VAR_SECTION:
625 			n = gint(&p);
626 			add_var_table((sysvar) ?
627 				&list_sysvar_tables : &list_var_tables, p, n);
628 			p += n;
629 			break;
630 		case END_SECTION:
631 			return (0);
632 		default:
633 			/*
634 			 * Unrecognized section type.
635 			 */
636 			return (-1);
637 		}
638 	}
639 }
640 
641 /*
642  * Set up a user command table, based on a "lesskey" file.
643  */
644 	public int
645 lesskey(filename, sysvar)
646 	char *filename;
647 	int sysvar;
648 {
649 	register char *buf;
650 	register POSITION len;
651 	register long n;
652 	register int f;
653 
654 	if (secure)
655 		return (1);
656 	/*
657 	 * Try to open the lesskey file.
658 	 */
659 	filename = shell_unquote(filename);
660 	f = open(filename, OPEN_READ);
661 	free(filename);
662 	if (f < 0)
663 		return (1);
664 
665 	/*
666 	 * Read the file into a buffer.
667 	 * We first figure out the size of the file and allocate space for it.
668 	 * {{ Minimal error checking is done here.
669 	 *    A garbage .less file will produce strange results.
670 	 *    To avoid a large amount of error checking code here, we
671 	 *    rely on the lesskey program to generate a good .less file. }}
672 	 */
673 	len = filesize(f);
674 	if (len == NULL_POSITION || len < 3)
675 	{
676 		/*
677 		 * Bad file (valid file must have at least 3 chars).
678 		 */
679 		close(f);
680 		return (-1);
681 	}
682 	if ((buf = (char *) calloc((int)len, sizeof(char))) == NULL)
683 	{
684 		close(f);
685 		return (-1);
686 	}
687 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
688 	{
689 		free(buf);
690 		close(f);
691 		return (-1);
692 	}
693 	n = read(f, buf, (unsigned int) len);
694 	close(f);
695 	if (n != len)
696 	{
697 		free(buf);
698 		return (-1);
699 	}
700 
701 	/*
702 	 * Figure out if this is an old-style (before version 241)
703 	 * or new-style lesskey file format.
704 	 */
705 	if (buf[0] != C0_LESSKEY_MAGIC || buf[1] != C1_LESSKEY_MAGIC ||
706 	    buf[2] != C2_LESSKEY_MAGIC || buf[3] != C3_LESSKEY_MAGIC)
707 		return (old_lesskey(buf, (int)len));
708 	return (new_lesskey(buf, (int)len, sysvar));
709 }
710 
711 /*
712  * Add the standard lesskey file "$HOME/.less"
713  */
714 	public void
715 add_hometable(envname, def_filename, sysvar)
716 	char *envname;
717 	char *def_filename;
718 	int sysvar;
719 {
720 	char *filename;
721 	PARG parg;
722 
723 	if (envname != NULL && (filename = lgetenv(envname)) != NULL)
724 		filename = save(filename);
725 	else if (sysvar)
726 		filename = save(def_filename);
727 	else
728 		filename = homefile(def_filename);
729 	if (filename == NULL)
730 		return;
731 	if (lesskey(filename, sysvar) < 0)
732 	{
733 		parg.p_string = filename;
734 		error("Cannot use lesskey file \"%s\"", &parg);
735 	}
736 	free(filename);
737 }
738 #endif
739 
740 /*
741  * See if a char is a special line-editing command.
742  */
743 	public int
744 editchar(c, flags)
745 	int c;
746 	int flags;
747 {
748 	int action;
749 	int nch;
750 	char *s;
751 	char usercmd[MAX_CMDLEN+1];
752 
753 	/*
754 	 * An editing character could actually be a sequence of characters;
755 	 * for example, an escape sequence sent by pressing the uparrow key.
756 	 * To match the editing string, we use the command decoder
757 	 * but give it the edit-commands command table
758 	 * This table is constructed to match the user's keyboard.
759 	 */
760 	if (c == erase_char || c == erase2_char)
761 		return (EC_BACKSPACE);
762 	if (c == kill_char)
763 		return (EC_LINEKILL);
764 
765 	/*
766 	 * Collect characters in a buffer.
767 	 * Start with the one we have, and get more if we need them.
768 	 */
769 	nch = 0;
770 	do {
771 	  	if (nch > 0)
772 			c = getcc();
773 		usercmd[nch] = c;
774 		usercmd[nch+1] = '\0';
775 		nch++;
776 		action = ecmd_decode(usercmd, &s);
777 	} while (action == A_PREFIX);
778 
779 	if (flags & EC_NORIGHTLEFT)
780 	{
781 		switch (action)
782 		{
783 		case EC_RIGHT:
784 		case EC_LEFT:
785 			action = A_INVALID;
786 			break;
787 		}
788 	}
789 #if CMD_HISTORY
790 	if (flags & EC_NOHISTORY)
791 	{
792 		/*
793 		 * The caller says there is no history list.
794 		 * Reject any history-manipulation action.
795 		 */
796 		switch (action)
797 		{
798 		case EC_UP:
799 		case EC_DOWN:
800 			action = A_INVALID;
801 			break;
802 		}
803 	}
804 #endif
805 #if TAB_COMPLETE_FILENAME
806 	if (flags & EC_NOCOMPLETE)
807 	{
808 		/*
809 		 * The caller says we don't want any filename completion cmds.
810 		 * Reject them.
811 		 */
812 		switch (action)
813 		{
814 		case EC_F_COMPLETE:
815 		case EC_B_COMPLETE:
816 		case EC_EXPAND:
817 			action = A_INVALID;
818 			break;
819 		}
820 	}
821 #endif
822 	if ((flags & EC_PEEK) || action == A_INVALID)
823 	{
824 		/*
825 		 * We're just peeking, or we didn't understand the command.
826 		 * Unget all the characters we read in the loop above.
827 		 * This does NOT include the original character that was
828 		 * passed in as a parameter.
829 		 */
830 		while (nch > 1)
831 		{
832 			ungetcc(usercmd[--nch]);
833 		}
834 	} else
835 	{
836 		if (s != NULL)
837 			ungetsc(s);
838 	}
839 	return action;
840 }
841 
842